The U.S. faces a growing number of potential terror threats from extremists in Syria and other countries and must do more at home to fight jihadist propaganda to prevent so-called "lone wolf'' attacks, according to two new studies, including one from the former leaders of the Sept. 11 commission.

Al Qaeda has become more diffuse—much of its core structure has been weakened, but it has expanded through a number of regional affiliate groups, according to a threat assessment from the Bipartisan Policy Center's Homeland Security Project, which is chaired by former Sept. 11 commission chiefs Thomas Kean and Lee Hamilton.

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Security forces manned the U.S. Embassy in Manama, Bahrain, early last month after Washington ordered it and other diplomatic outposts closed over a terror threat.
Associated Press

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A fighter from the Islamist Syrian group Jabhat al-Nusra last month.
Reuters

"Even though core al Qaeda may be in decline, 'al Qaeda-ism,' the movement's ideology, continues to resonate and attract new adherents," according to the report, released a few days ahead of the 12-year anniversary of the 2001 attacks.

As a result, al Qaeda has a presence in some 16 different areas around the globe, the report concludes—double the number five years ago.

The report's authors warn of the potential long-term threat posed by Jabhat al-Nusra, an al Qaeda affiliate now fighting the Assad regime in Syria. While the group is now focused on that battle, the report warns it "could create an organization with the intention and capability to attack the West itself."

"Potential jihadi access to the vast stockpile of chemical weapons assembled by the Assad regime and scattered across Syria is a potential game-changer," it says, warning the weapons could be smuggled elsewhere. Such concerns are part of what is complicating a congressional debate over military strikes on Syria for the regime's alleged use of chemical weapons.

More broadly, the report warns violent extremist groups in Arab Spring countries like Egypt—and African countries like Mali—provide multiple arenas in which regional conflicts could metastasize into international terror threats.

Those alarms are echoed in a separate report issued by the Soufan Group, a firm founded by former Federal Bureau of Investigation agent Ali Soufan, who worked on high-profile terrorism cases. "Terrorists and extremists are, in many ways, in a stronger position today than in the past," the Soufan report says.

Domestically, the Bipartisan Policy Center's report notes that by one measure, the threat has declined in recent years. In 2009, for instance, 44 alleged jihadists were indicted in the U.S., according to the BPC, and that number has declined every year since. In the first eight months of 2013, six such individuals were indicted.

To face the changing threat, the bipartisan group's recommendations include creation of a permanent investigative panel, modeled after the National Transportation Safety Board, to launch probes after terror attacks into what clues authorities may have missed. The group also recommends the Department of Homeland Security create a position focused on countering jihadist ideology and propaganda.

Countering jihadi recruitment and propaganda is the main focus of the report from the Soufan Group. The report studies countries where governments have launched programs to counter extremist rhetoric and indoctrination, and it found the U.S. trails many such countries in instituting such programs.

Both the BPC and Soufan reports say such work is critical to deterring lone-wolf terror suspects—those inspired and trained online, without any close connection to formal terror groups. They cite this year's Boston Marathon bombing as a lone-wolf style attack, which counterterrorism officials say are difficult to detect ahead of time.

In an interview, Mr. Soufan said not intervening in Syria could give violent extremists more sway, and more followers. "If we ignore the situation in Syria, as we did in the last 21/2 years, somebody is going to fill the void," he said, comparing it with Afghanistan in the 1990s. "Every time there is a vacuum, extremists have been able to fill the void."

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